Tropical African forest is the one of the most interesting spots in the world from the atandpoint of bioactive natural product research. It is rich in plant species which are adaptive in a coevolution with regard not only to climatic factors but also to complex biological interactions. For such adaptation, a chemical defense system may be one pssible strategy. Thus, we have surveyed useful plants of the savanna woodland of Tanzania, and chemically studied their bioactive constituents as well as the biological or physiological significance. The main survey was conducted on Oct.27th - Oct.22nd at the Mahale Moutains National Park located along Lake Tanganyika in Tanzania, where Dr.Nishida (Kyoto Univ.) and his colleagues have carried out the chimpanzee socioecological study for a long time. We had already listed up some plants of biological and physiological significance, on the basis of the results from the previous survey conducted here in 1991. Also we could well select chimpanzee med
… Moreicinal plants in kind cooperation with Dr.Nishida. Furthermore, we tried to collect informations of tradirional plant-use from native people.We have collected a total of 19 plant species including 12 species of chimpanzee medicinal plant, 3 species of medicinal plant locally used. Among the plants collected, 16 species have thus far identified.Each extract has been tested for several biological activities, e.g.antiparasitic activities including antischistosomal, antimalarial, and antimoebic activities, several enzyme inhibition activities, cyte toxic activities, antibiotic activities against insects and microbials, and active oxygene generation inhibition or scavenging activities. Antiparasitic activities were found in 10 species of plant, and 9 out of these 10 were those collected as chimpanzee medicila plant. Thus, chimpanzee in the wild may often use some plants as antiparasitic medicine. In particular, strong antischistosomal activities were found in Erythrina abyssinica, Trema orientalis, Stephania abyssinica, Combretum molle and Vernonia amygdalina. In E.abyssinica and Aspilia mossambicensis, antimalarial activity was clearly detected, and antiamoebic activity was also in E.abyssinica. From V.amygdalina which we have hitherto extensively studied the antiparasitic agents, new steroids were isolated. The antiparasitic activities of these steroids are now in progress. E.abyssinica and Senna spectabilis showed inhibitory activity of aromatase, Senna spectabilis and S.abyssinica inhibited superoxide anion genaration, and T.orientalis showed insect antifeedant activity.帰国後、それぞれの一部を各種溶媒で抽出し、野生チンパンジー薬用植物(Erythrina abyssinica,Aspilia mossabicensisなど12種)については抗住血吸虫活性、抗マラリア、抗赤痢アメーバーなど抗寄生虫活性、さらには各種酵素阻害活性、細胞毒性活性、昆虫や微生物に対する抗生物活性、活性酸素産生(消去)活性などの生理活性試験に供した。また、その他の植物についても順次上記の各種試験に提出中である。これまでのところ、抗寄生虫活性に関する結果が全体的に整いつつある(一部は前回の試験結果の再確認:今回の試料にて活性物質の精製・単離を行う)。チンパンジーの薬用植物12種中9種に何らかの抗寄生虫活性が認められるとの興味ある結果が得られた。抗住血吸虫活性として特筆される植物は、E.abyssinica、Trema orientalis、Stephania abyssinica、Combretum molle、Vernonia amygdalinaであった。抗マラリア性植物としては、E.abyssinica、A.mossambicensisが顕著なものであった。E.abyssinicaには抗赤痢アメーバー活性も認められた。なお、V.amygdalinaについては"野生霊長類の薬用植物利用仮説"を実証するため、現在我々のグループが最も力を入れている研究である。そこで、これまでの結果を背景にさらに詳細に活性遊離ステロイドの研究を行った。その結果、新規なステロイドが数種単離・構造決定できた。現在これら化合物の抗寄生虫活性を検定中である。その他興味ある活性を発現した植物として、E.abyssinicaとSenna spectabilisにアロマターゼ阻害活性が、S.spectabilisやS.abyssinicaには活性酸素産生抑制活性が、T.orientalisに昆虫生育阻害活性が認められた。 Less